feat(GaussDB): add gaussdb opengauss parameter template resource

[houpeng80]

What this PR does / why we need it:
add gaussdb opengauss parameter template resource
Which issue this PR fixes:
(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)
fixes #xxx

Special notes for your reviewer:

Release note:

  add gaussdb opengauss parameter template resource

PR Checklist

• Tests added/passed.

make testacc TEST=./huaweicloud/services/acceptance/gaussdb/ TESTARGS='-run TestAccOpenGaussParameterTemplate_'
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./huaweicloud/services/acceptance/gaussdb/ -v -run TestAccOpenGaussParameterTemplate_ -timeout 360m -parallel 4
=== RUN   TestAccOpenGaussParameterTemplate_basic
=== PAUSE TestAccOpenGaussParameterTemplate_basic
=== RUN   TestAccOpenGaussParameterTemplate_copy
=== PAUSE TestAccOpenGaussParameterTemplate_copy
=== CONT  TestAccOpenGaussParameterTemplate_basic
=== CONT  TestAccOpenGaussParameterTemplate_copy
--- PASS: TestAccOpenGaussParameterTemplate_basic (49.02s)
--- PASS: TestAccOpenGaussParameterTemplate_copy (60.20s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/gaussdb   60.249s

• Documentation updated.

• Schema updated.

• CheckDeleted.

  • a. During query operation (Read Context)
    aa. Resource not found
    
    ab. Related resources (parent resources) not found
    >>>>>> Paste the screenshot here <<<<<<
    -->
  • b. During delete/disassociate/unbind operation (Delete Context)
    ba. Resource not found
    .
    bb. Related resources (parent resources) not found
    >>>>>> Paste the screenshot here <<<<<<
    -->

[Jason-Zhang9309]

/lgtm